The present invention relates to a method and an apparatus for controlling the airflow rate in an air conditioner.
As an airflow rate control apparatus in an air conditioner, for example, an automatic airflow rate control apparatus in an air conditioner for use in vehicles is constructed as shown in FIG. 1. More particularly, with reference to FIG. 1, reference numeral 1 designates a power supply, numeral 2 designates a fuse, numeral 3 designates a fan switch, numeral 4 designates a fan, numeral 5 designates a resistor for regulating the airflow rate, numeral 6 designates a fan transfer switch, numeral 7 designates an actuator for driving an air-mix damper, numeral 8 designates an air-mix damper, numeral 9 designates a cooler and numeral 10 designates a heater. In this control apparatus, the flow rate of the air flow supplied from the fan 4 is adapted to be varied in a step-wise manner according to the opening angle of the air-mix damper 8. In some modified control apparatus, in place of the aforementioned fan transfer switch 6, there is provided a potentiometer and, by means of this potentiometer, an air-flow rate is controlled in a stepless manner, for example, as shown in FIG. 2.
In either of these known control apparatus, the airflow rate is preset depending upon an air-mix damper position. Therefore, even under the condition, for example, that the desired temperature regulation can be effected with an air-mix damper placed at the MAX COOL position and the fan operated at an L (low)-level, since such an operating condition is not preset, the air-mix damper opens somewhat to the heater side so as to slightly raise the temperature of the blown out air to compensate for this, the airflow rate of the fan is increased, so that the same cooling capability as that obtained under the condition of the MAX COOL position of the air-mix damper and the L-level operation of the fan may be eventually realized. In other words, operation is effected while wastefully reheating cooled air and increasing the airflow rate of a fan, and therefore, the operation is not only inefficient but is also associated with an energy loss.
Furthermore, FIG. 3 shows the relationship between the temperature deviation and airflow rate in another known control apparatus in which the airflow rate is controlled by the temperature deviation between the room temperature and a preset temperature. However, in this case, when the temperature deviation becomes small, the airflow rate of a fan is decreased and hence the cooling capability or the heating capability is also lowered. Therefore, this type of apparatus has a disadvantage in that even if the air-mix damper is placed at the MAX COOL position or the MAX HOT position, a temperature deviation would still remain. More particularly, for example, even under the condition that a set temperature can be realized when the air-mix damper is placed at the MAX COOL position and the airflow rate is held at the maximum, as the room temperature approaches the set temperature, the airflow rate would be decreased and hence the cooling capability would become insufficient. This means that it is impossible to reach the set temperature and thus this apparatus is very unsuitable.